What do I need to know about sunscreen ingredients?

Sunscreens contain filters that reflect or absorb UV rays. There are two main types of sunscreens:

Organic. Also called chemical sunscreens, organic sunscreens absorb UV radiation and convert it to a small amount of heat. This group of active ingredients is the most widely used in sunscreens. Organic sunscreens might contain avobenzone, cinoxate, ecamsule, menthyl anthranilate, octyl methoxycinnamate, octyl salicylate, oxybenzone or sulisobenzone.

Insect repellent. Keep in mind that it's typically recommended that insect repellent be applied no more often than every six hours. When using this type of combination product, reapply a sunscreen without insect repellent after two hours outdoors or after swimming or heavily sweating.

Some sunscreens also contain the antioxidant retinyl palmitate, a form of vitamin A or retinol. Antioxidants are substances that neutralize free radicals — unstable oxygen molecules that break down skin cells and cause wrinkles. While concerns have been raised about sunscreens containing retinyl palmitate, research currently suggests it's safe. However, recommendations regarding safety for use during pregnancy aren't available. If you're concerned, consider avoiding sunscreens containing this ingredient during pregnancy.

Are some brands of sunscreen better than others?

Brand matters less than how you use the product. In general, look for water-resistant, broad-spectrum coverage with an SPF of at least 15. Check the sunscreen's expiration date, and follow the directions on the label.

Also, keep in mind that labeling guidelines for sunscreen in the United States are changing. Under new Food and Drug Administration guidelines:

Only sunscreens that offer protection from both UVA and UVB rays can advertise broad-spectrum coverage on the label.

Only broad-spectrum sunscreens with an SPF of 15 or higher can claim to reduce the risk of skin cancer or prevent early skin aging.

Any claims about reducing the risk of skin cancer or early skin aging must be accompanied by other sun protection measures, such as wearing protective clothing and avoiding midday sun.

Sunscreens with an SPF of at least 2 but less than 15 can advertise protection from sunburn only — not protection from skin cancer or early skin aging.

Sunscreens can't be advertised as sweatproof or waterproof.

Sunscreens that pass a water resistance test can be labeled "water resistant" for either 40 or 80 minutes, as long as they also include instructions to reapply after 40 or 80 minutes of swimming or sweating, immediately after towel drying and at least every two hours.

Ultimately, it's important to find a sunscreen you like. If you don't care for the sunscreen, you're not as likely to use it consistently.

Should I use a spray sunscreen or a lotion?

The kind of sunscreen you use is up to you. However, certain types of sunscreen work best on specific areas of the body. If you have dry skin, you might prefer a cream — especially for your face. A gel or spray might work better for areas covered with hair, such as the scalp or a man's chest. Parents often prefer sprays because they're easy to apply on children. When using spray sunscreen, be sure to apply a generous and even coating. Avoid inhaling the product.

Do I need to apply sunscreen even if I wear cosmetics that contain sunscreen?

It depends on how much time you'll be spending in the sun. If you wear cosmetics that contain sunscreen, such as moisturizer, foundation or lipstick, you'll need to reapply them every two hours when outside or also apply a separate sunscreen.

If you won't be spending much time outdoors and you don't wash your face or heavily sweat during the day, it's OK to apply a moisturizer containing sunscreen just once in the morning.

What else is important to remember about using sunscreen?

Use sunscreen on all skin surfaces that will be exposed to sun, such as your face, ears, hands, arms and lips. If you don't have much hair on your head, apply sunscreen to the top of your head or wear a hat.

Reapply sunscreen every two hours — and immediately after swimming or heavy sweating.

Remember that sand, water, snow and concrete reflect sunlight and make it even more important to use sunscreen.

Since UV light can pass through clouds, use sunscreen even when it's cloudy.

You can apply sunscreen to children as young as age 6 months. Keep younger children in the shade as much as possible.

Use sunscreen year-round, but don't let any product lull you into a false sense of security about sun exposure. A combination of shade, clothing, sunscreen and common sense is your best bet.

Schnorr CE, et al. Vitamin A supplementation in rats under pregnancy and nursing induces behavioral changes and oxidative stress upon striatum and hippocampus of dams and their offspring. Brain Research. 2011;1369:60.

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